Two new species of the phytoseiid genus Neoseiulus (Acari: Mesostigmata) from Steppe zone of Ukraine

Two new species of phytoseiid mites of the genus Neoseiulus (Acari: Mesostigmata) from Steppe zone of Ukraine are described. Detailed descriptions, drawings, measurements, diagnosis of the new species, and the data of mite locations are given.


INTRODUCTION
Mites of the family Phytoseiidae (Acari: Parasitiformes) are well known as regulators of magnitude of population of small phytophagous microarthropods inhabiting terrestrial plants. During a study of mites on plants of maritime landscape of Steppe zone of Ukraine (territory of Black Sea Biosphere Reserve National Academy of Sciences of Ukraine) two unknown phytoseiid species were found. Their descriptions, drawings, and diagnoses are given in this paper.

MATERIALS AND METHODS
Only single specimen for each of the two new species of phytoseiid mites (Parasitiformes: Phyto-seiidae) were found in the collected samples in 2015 on plants of Black Sea Biosphere Reserve. The mites were kept in 70% alcohol, and then mounted on microscope slides in Hoyer's medium for examining under microscope MBI-3 (LOMO). A phase contrast attachment KF-1 (LOMO) and a camera Lucida apparatus RA-6 (LOMO) were used for the drawings. Setal nomenclature and idiosomal setal pattern follows that proposed by Lindquist and Evans (1965), as adapted by Rowell et al. (1978) for Phytoseiidae. Nomenclature of setae on legs follows that of Evans and Till (1979). Nomenclature of dorsal solenostomes follows that Athias-Henriot (1975). The nomenclature of spermatheca structures follows Kolodochka (1990). The apical tooth is not included in the number of teeth of cheliceral digits. Measurements are presented in micrometers (µm).
Holotypes of both new species are deposited in the Institute of Zoology, National Academy of Sciences of Ukraine (IZNASU), Kiev.
The new species distinctly differs from the latter by presence of 6 pairs of dorsal solenostomes (gd5 absent) instead of 7 as in N. bicaudus, by diverse proportions of setae lengths in posterior part of dorsal shield; by seta J5 twice longer, by presence of dorsal setae J5, S4, S5, Z4, Z5 serrated (instead of Z5 serrated only in N. bicaudus); and by 7 teeth on fixed digit of chelicera instead of 6 in N. bicaudus.
There is no data about ecological characters of the new species. Description -Female. Dorsal shield ( Fig. 2A) weakly sclerotized, elongated, with constrictions on level of setae z4, R1, as well as between S5 and Z5; feebly net-like reticulated in posterior part, with 4 pairs of small distinct solenostomes (gd1, gd2, gd6, gd9), and 17 pairs acute, thin, flexible, short and slightly different in length setae except elongate Z5. Dorsal setae smooth except Z5 weakly serrated. Setae J5 short, each with one barb (Fig. 2B). Length of seta j3 slightly longer then distance from own base to base of seta z2. Setae z2 and z4 twice shorter than distance between their bases to bases of next setae. Seta S4 longer than S3 and S5. Seta Z4 shorter than distance between its base to solenostome gd9 ( Fig. 2A). All ventral setae thin, acute, and smooth (Fig. 2C). Sternal shield weakly sclerotized, with 3 pairs of setae (St1-St3) and 2 pairs of pores. Seta St3 on post-lateral apophyses of sternal shield. Setae St4 each on small separate metasternal platelets each with pore. Genital shield with one pair of setae (Ge). Sclerotized line-like transversal stria between genital and ventrianal shield are the 4th and 5th pairs of genital sigilla. Genital sigilla 6th pair (sgpa) of semilunar shape, on interscutal membrane, posteroparaxially to setae ZV1 (Fig. 2C). Ventrianal shield wider than genital shield, near pentagonal in shape with convex anterior margin, lateral margins with light constrictions and thin striation in circum-anal area. Three pairs of short preanal setae JV1, JV2, ZV2 on ventrianal shield. Solenostomes gv3 crescentic, disposed between setae JV2 and behind their level. Four pairs of ventral setae (ZV1, ZV3, JV4 and JV5) and four small oval platelets on the integument surrounding the ventrianal shield (Fig. 2C). Chelicerae normal in size. Fixed digit with 5 distinct denticles (two subapical and three smaller teeth in separate row), movable digit with one tooth (Fig. 2D). Metapodal plates elongate, anterior platelet significantly smaller and narrower than posterior plate (Fig. 2E). Spermatheca with funnel bell-shaped and wall thickened, atrium small, and cervix very short (Fig. 2F). Peritremes long, extending beyond bases of setae j3 ( Fig. 2A). Posterior part of peritremal shield broad, curved, widened because of the fusing of its inner edge with exopodal scutum of leg IV (Fig. 2G). Leg IV with three smooth macrosetae: longest on basitarsus with small clava on tip, markedly shorter and acute on tibia and genu (Fig. 2H). No macrosetae on other legs. Genu II with 8 setae (2 al -2ad, 2 pd / 1 av, 0 pv -1 pl) (Fig. 1I). Notes -Neoseiulus probatus n. sp. closely resembles N. bicaudus but differs from it by occurrence of only 4 pairs of dorsal solenostomes (gd4, gd5 and gd8 absent); by thin and flexible dorsal setae, by setae J5 with one notch each, by seta JV5 smooth, by bell-shaped funnel of spermatheca with thick wall, and by fissured anal pores as compared with 7 pairs dorsal solenostomes, comparatively thickened and rigid dorsal setae, setae J5 smooth, seta JV5 serrate, cup-shaped and thin wall of spermatheca funnel, point anal pores in N. bicaudus.

Neoseiulus probatus
N. probatus n. sp. differs from N. ponticus n. sp. by presence of 4 dorsal solenostomes against 6 pairs in the latter; by different sizes of dorsal and ventrianal shields; by setae J5 shorter and setae Z5 longer; by seta S4 longest in row of setae S2-S4-S5 (against S5 longest in the latter); by 5 teeth on fixed digit of chelicera against 7 teeth as in N. ponticus.
There is no data about ecological characters of the new species.